Frame corner structure

ABSTRACT

An improved corner frame structure and method of manufacturing it is provided. The corner is effected by joinder of channelled members by a solid bracelet having legs extending at the desired angle. 
     Each leg is provided with a pair of spaced apart depressions. Into these depressions, tongues are struck down to bind and urge the adjacent frame members together.

This is a division, of application Ser. No. 831,521 filed Sept. 8, 1977 and now U.S. Pat. No. 4,192,624.

BACKGROUND OF THE INVENTION

This invention relates to frame structures and more particularly to the structure of corners for such frames.

It has been common practice in the manufacture of aluminum window and door frames to use mitred joints which are either secured by welding or screws to support a piece joining the adjacent channels.

However, the weld joints and the screw joints have become expensive because of their high labour content.

They also have several individual shortcomings. The welded joints are difficult to maintain and the screw joints tend to loosen. With both types of joints, however, there has been the problem of strength. To provide strength, a relatively thick gauge of metal has to be provided to prevent warping.

The screw joints, if not countersunk, normally had to be provided on a surface of the window which if not visible, restricted the hinge movement, and if not hidden from view was exposed to the elements so that there was provided a further entry for the elements and deterioration of the structure.

Furthermore, the screw joints were not secure.

CONSIDERATION OF THE PRIOR ART

The most relevant art of which the applicants are aware is as follows:

    ______________________________________                                         U.S. Pat. No. 1,745,818                                                                        Trombly et al                                                                              Feb. 4, 1930                                       U.S. Pat. No. 2,101,349                                                                        Sharp       Dec. 7, 1937                                       U.S. Pat. No. 3,342,514                                                                        Ivanhoe et al                                                                              Sept. 19, 1967                                     U.S. Pat. No. 3,767,237                                                                        Suchowski   Oct. 23, 1973                                      ______________________________________                                    

Insofar as they are understood, the latter two patents require some further agency to effect the joint between the frame and the bar and the Sharp patent structure depends upon resilient barbed engagement between hard and soft metal to effect the joint.

The most relevant prior art appears to be Trombly, U.S. Pat. No. 3,745,818. However, it will be noted that in that structure only single depressions are formed on each leg and the struck up tongues which engage the depressions are previously formed.

These differences in structure and production lead to important differences in the final result as will be apparent from the description which follows.

SUMMARY OF THE INVENTION

With the disadvantages of the prior art in mind, it is the principal object of the present invention to provide a mitred corner frame structure which is strong, economical to produce and pleasing to the eye.

Generally, in the present invention, a solid bracket having a pair of legs at the desired angle is inserted, one leg in each channel of an adjacent frame element. On the surfaces of the bracket to which the frame elements are to be secured, a pair of depressions are provided, two on each leg.

The corner structure is then placed in a jig and a die sequentially strikes out the two pairs of tongues and urges them into engagement with the interior support bracket.

However, the actual process, the structure and the advantages which flow therefrom will be more fully understood from the following description of the invention and the drawings, in which a specific embodiment is described by way of example and in which:

FIG. 1 is a general perspective view of a mitred frame in accordance with the present invention;

FIG. 2 is a section through a corner prior to effecting the junctions in accordance with the present invention;

FIG. 3 is a further section of the corner illustrated in FIG. 2 immediately prior to impingement of the second part of the tool die; and

FIG. 4 is a section through a corner in accordance with the present invention.

As shown in the drawings and more particularly FIG. 1, the structure which the present invention exhibits does not require any fastening elements apart from the structural elements themselves.

As shown in FIG. 1, each frame comprises frame elements 20 which are provided with mitred end surfaces 24 and in the final assembled product the frame, as will be evident from the description, may be made of any desired shape. The only essential criteria are the angles defined by the legs of the securing brackets.

As shown, each corner structure comprises a bracket 100 which in the embodiments illustrated each have two legs 101 and 102 which define a right angle.

The legs of bracket 100 fit within the channels defined by the frame members or elements 20. The frame members 20 and 21 in FIG. 1 have a substantially rectangular form which slidably receives the corresponding legs 101 and 102 of the bracket 100.

For convenience, the surfaces and walls of frame member 20 will be identified as 30, 31, 32 and 33 and those of member 21 as 40, 41, 42 and 43 respectively.

The bracket 100 has a plane, substantially unbroken surface along the extension surfaces of legs 101 and 102. However, the ends are chamfered to permit facility of insertion into the channel members and at the internal junction of legs 101 and 102 a cavity 103 is provided and on each of legs 101 and 102, two triangular depressions--104 and 105 on leg 101 and 106 and 107 on leg 102--are provided.

For the purposes of this description, it will be understood that depressions 104 and 106 will be described as the inner depressions and 105 and 107 will be referred to as outer depressions.

Initially, the corner joint is assembled as illustrated in FIG. 2. The corner is then placed in a right-angled jig. The two frame members 20 and 21 are free to move. It will be noticed that there is in the initial position shown in FIG. 2 an opening in the mitre.

As the die 150, shown diagrammatically in FIG. 3, moves in, it first engages surfaces 30 and 40 to cut and strike out tongues 130 and 140.

This initial action drives the respective frame elements 20 and 21 towards each other, that is in the directions of the arrow towards the corner.

As the tongues 130 and 140 have been cut and they are bent, they make engagement with the remote surface of depressions 105 and 107 from the corner.

Immediately in sucession, the second phase of the die impinges on surfaces 30 and 40 to strike tongues 131 and 141.

Depressions 104 and 106 are of reduced depth with respect to depressions 105 and 107. They are reduced in depth by the gauge of channel walls 30 and 40.

The action of the successive striking ensures that the corner is closed and locked. The interior junction of the bar with its cavity 103 permits the migration of the metal on the internal surfaces to be accommodated without distortion.

It will also be observed that the depressions 104 and 105 on leg 101 and depressions 106 and 107 on leg 102 are on opposite sides of the midline or axis of their respective sidewalls 30 and 40. Since channel members 20 and 21 are aluminum, the tongues which are stuck out are also on opposed sides of the midline.

This disposition precludes or limits the possibility of fracture or weakening of the frame if all the tongues are stuck out in alignment.

From the foregoing description, it will be seen that no other joining or fastening element is required to effect the junction.

As can be seen in FIG. 3, successive striking of tongues 130 and 140, and tongues 131 and 141, is accomplished by using a die having dimensions that enables first contact with tongues 130 and 140, and traversal of the walls 30 and 40, before contact is made with tongues 131 and 141. That is, the element of the die striking tongues 131 and 141 is shorter by the gauge of walls 30 and 40 than the element of the die that strikes tongues 130 and 140.

It will also be evident that a minimum amount of labour is required. The joint at least from external purposes is clean and minimizes the exposure of the interior of the frame to the elements. Furthermore, the joint has been found to be extremely strong.

It will also be evident that any angled joint may be made with equal facility. 

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
 1. A method of manufacturing a corner structure for window frames and the like comprising:providing a pair of metal frame members each having a longitudinally extending channel extending from a mitred end, each channel being defined by opposed sides, providing a bracket having a pair of angularly disposed legs slidably receivable in the channels of said frame members, each leg having a surface opposed to a surface on an adjacent leg, and each opposed surface having a pair of longitudinally spaced depressions therein, the depression in each leg nearest the other leg having a depth less than the depth of the other depression in the leg by at least the thickness of a side of the channel of a frame member, inserting the bracket legs into the channels of the frame members to cause the mitred ends of the frame members to abut, forcing a die against the frame member channels to strike out tongues from each frame member channel into the deeper depressions in the bracket arms and immediately thereafter to strike out tongues from each frame member into the depressions of less depth in the bracket arms to urge the mitred ends of the frame members together, each tongue extending in a direction away from the respective mitred end.
 2. A method according to claim 1 wherein the depressions in the bracket arms are triangular, the method including causing the die to strike out the tongues so that each tongue engages at least a part of both surfaces of the respective depression.
 3. A method according to claim 1 wherein the bracket has a recessed internal corner, and the method includes causing metal to be displaced from the mitred ends of the frame members into the recessed internal corner of the bracket by said forcing of the die against the frame member channels to urge the mitred ends of the frame members together.
 4. A method according to claim 1 wherein the depressions in each bracket leg are laterally offset relative to one another, and said die strikes out correspondingly laterally offset tongues.
 5. A method of manufacturing a corner structure for window frames and the like comprising:providing a pair of metal frame members each having a longitudinally extending channel extending from a mitred end, each channel being defined by opposed sides, providing a bracket having a pair of angularly disposed legs slidably receivable in the channels of said frame members, each leg having a surface opposed to a surface on an adjacent leg, and each opposed surface having a pair of longitudinally spaced depressions therein, the depression in each leg nearest the other leg having a depth less than the depth of the other depression in the leg by at least the thickness of a side of the channel of a frame member, inserting the bracket legs into the channels of the frame members to cause the mitred ends of the frame members to abut, forcing a die, having four striking elements, such that the striking elements are of a dimension that permits two of the striking elements to make contact and traverse the walls of the opposed sides of the corner structure, before the other two striking elements make contact with said opposed sides, against the frame member channels to strike out tongues from each frame member channel into the deeper depressions in the bracket arms and immediately thereafter to strike out tongues from each frame member into the depressions of less depth in the bracket arms to urge the mitred ends of the frame members together, each tongue extending in a direction away from the respective mitred end. 